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Three hundred million tires are wasted and scrapped every year in California; that is 1.1 tires per person per year in California. Problems caused by wasted tires are created mosquito nesting grounds, possible fire hazards, and a waste space. Edincliler et al (2004) experimented with using different recycled materials for highway applications. They found that the shear modulus and damping value of sand-tire buffings mixtures are higher than those of tire buffings alone. This experiment involved the utilization of recycled tires, tested by mixing clay soils and shredded rubber tire to try and improve the strength of the soil. Kaolin clay and Bentonite clay are the soils mixed with different percentages of tires (0%, 2%, 4%, 6%, 8%, 10%, 15%, 20%, 25%, and 30%). Several different tire sizes were also examined in this study. In particular, tires of sizes 6-14 mesh, 10-30 mesh, 30-50 mesh, 50-80 mesh and 80-200 mesh were used. Samples were prepared with the use of the Harvard Miniature Compaction procedure and tested in an Unconfined Compression apparatus to obtain the shear strength. Based on the results of the study, for Kaolin clay, adding 8% shredded rubber of size 10-30 mesh produced the largest shear strength. Meanwhile, for Bentonite clay, adding 4% shredded rubber of size 10-30 produced the largest shear strength. Moreover, for the Bentonite samples, the peak strength was obtained on the wet side of the optimum moisture content, that is at a moisture content greater than the optimum moisture content. However, for Kaolinite samples, the peak strength was obtained on the dry side of the optimum moisture content (at moisture contents less than the optimum). By improving these different characteristics smaller foundations are needed for structures on the improved soil in comparison to structures on the original soil.